The beneficial use of lipolytic enzymes (E.C. 3.1.1.x) in food and/or feed industrial applications has been known for many years.
For instance, in EP 0 585 988 it is claimed that lipase addition to dough resulted in an improvement in the antistaling effect. It is suggested that a lipase obtained from Rhizopus arrhizus when added to dough can improve the quality of the resultant bread when used in combination with shortening/fat. WO94/04035 teaches that an improved bread softness can be obtained by adding a lipase to dough without the addition of any additional fat/oil to the dough. Castello, P. ESEGP 89-10 Dec. 1999 Helsinki, shows that exogenous lipases can modify bread volume.
The substrate for lipases in wheat flour is 1.5-3% endogenous wheat lipids, which are a complex mixture of polar and non-polar lipids. The polar lipids can be divided into glycolipids and phospholipids. These lipids are built up of glycerol esterified with two fatty acids and a polar group. The polar group contributes to surface activity of these lipids. Enzymatic cleavage of one of the fatty acids in these lipids leads to lipids with a much higher surface activity. It is well known that emulsifiers, such as DATEM, with high surface activity are very functional when added to dough.
Lipolytic enzymes hydrolyse one or more of the fatty acids from lipids present in the food which can result in the formation of powerful emulsifier molecules within the foodstuff which provide commercially valuable functionality. The molecules which contribute the most significant emulsifier characteristics are the partial hydrolysis products, such as lyso-phospholipids, lyso-glycolipids and mono-glyceride molecules. The polar lipid hydrolysis products, namely lyso-phospholipids and lyso-glycolipids, are particularly advantageous. In bread making, such in situ derived emulsifiers can give equivalent functionality as added emulsifiers, such as DATEM.
However, the activity of lipolytic enzymes has also been found to result in accumulation of free fatty acids, which can lead to detrimental functionality in the foodstuff. This inherent activity of lipolytic enzymes limits their functionality.
The negative effect on bread volume is often explained by overdosing. Overdosing can lead to a decrease in gluten elasticity which results in a dough which is too stiff and thus results in reduced volumes. In addition, or alternatively, such lipases can degrade shortening, oil or milk fat added to the dough, resulting in off-flavour in the dough and baked product. Overdosing and off-flavour have been attributed to the accumulation of free fatty acids in the dough, particularly short chain fatty acids.
The presence of high levels of free fatty acids (FFA) in raw materials or food products is generally recognised as a quality defect and food processors and customers will usually include a maximum FFA level in the food specifications. The resulting effects of excess FFA levels can be in organoleptic and/or functional defects.
In WO2005/087918 novel fungal lipolytic enzymes were identified from Fusarium species, such as Fusarium heterosporum CBS 782.83 which were shown to have a superior quality in certain applications. These enzymes were expressed in Hansenula polymorpha and were found to hydrolyse primarily fatty acids in the sn-1 position of galactolipids and phospholipids in dough.
The problem with some fungal lipolytic enzymes is that expression of the enzyme may be limited and therefore may be costly to produce. For example expression of the enzyme in high amounts suitable for commercial scale activities may be limited. The industry is interested in finding novel lipolytic enzymes which show enhanced expression, particularly if this can be achieved without compromising functionality and/or activity.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.